Maybe a surveyor skill in terraforming where you can only use it inside your tribe zone to get some exact (more exact the higher your surveyor skill) coords to use in building, but once you step outside your zone, you have no coords(you won't be building there). It wouldn't even have to be world coords, each tribe zone could have it's own set specific to the zone with (0,0) being the exact center of the zone. This would take care of the mathematics needed for building. Then you would need Cartography skill to make a player made map of the world, the better the skill, the better the map, but you would need papyrus and charcoal to draw the map, then if traded or sold to another player, they would then be able to look at it also.